Severe Storm Outlook Narrative (AC)
Issued by NWS
Issued by NWS
991 ACUS03 KWNS 211930 SWODY3 SPC AC 211929 Day 3 Convective Outlook NWS Storm Prediction Center Norman OK 0129 PM CST Thu Nov 21 2024 Valid 231200Z - 241200Z ...NO SEVERE THUNDERSTORM AREAS FORECAST... ...SUMMARY... Severe thunderstorms appear unlikely across the CONUS Saturday. ...Synopsis... Mid-level flow across the CONUS is forecast to become more zonal with time as prominent troughing on either coast gradually deamplifies. Ridging over the central CONUS will weaken and shift eastward as the East Coast trough moves offshore. To the west, strong mid-level flow will move inland across the Pacific Northwest and northern Rockies as the upper low cuts off southwest of BC. A weak surface low and cold front will move across the northern Rockies and intensify over the High Plains. High pressure over the eastern US will favor cool, dry and stable offshore flow across the eastern half of the country. ...Northwest and Northern Rockies... As the broad upper-level cyclone over the Pacific Northwest gradually devolves, a lead shortwave trough embedded within the stronger zonal flow will quickly eject eastward over the Northern Rockies. A weak surface low and trailing cold front will also move east with the stronger flow aloft. Area model soundings show weak destabilization is possible over parts of eastern OR and southern ID as forcing for ascent increases and low-level lapse rates steepen ahead of the front. While very limited, enough buoyancy (MUCAPE ~100-200 J/kg) may develop for a few lightning flashes with low-topped, mixed-phase, convective elements. Additionally, low-topped storms may approach near shore areas of OR/WA and northern CA. However, cool inland surface temperatures and weakening large-scale ascent should limit lightning chances inland. ..Lyons.. 11/21/2024 $$